Studies of the reticuloendothelial system and the clearance of particles from the circulation have continued. As detailed in Dr. Quinn's outline, a specific defect has been discovered in patients with AIDS syndrome. Such a defect may predispose these patients for dissemination of intracellular infection as is noted to occur in this group. This is felt to be a secondary defect rather than primary to development of the AIDS syndrome. Last year we reported striking changes in mononuclear phagocyte Fc receptor expression induced by pharmacologic glucocorticoid therapy. Studies of similarly treated normal volunteers were carried out to characterize changes in in vitro clearance. In each individual studied, subtle slowing of Fc receptor mediated clearance was demonstrated following clinically relevant glucocorticoid doses. Studies are in progress to evaluate possible sex differences in Fc-receptor mediated clearance in humans (as a possible reflection of previously demonstrated quantitative differences in receptor expression on monocytes from male and female subjects). In addition, the existence of familial abnormalities in clearance is being sought in the families of patients with systemic lupus erythematosus.